This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A062573 #22 Jul 04 2021 07:52:21 %S A062573 2,3,7,29,41,67,1327,1399,2027,69371,86689,355039 %N A062573 Numbers k such that 7^k - 6^k is prime. %C A062573 Terms greater than 1000 often correspond only to strong probable primes. %H A062573 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=7%5Ep-6%5Ep">Top probable primes of the form 7^p-6^p</a> %e A062573 7^2 - 6^2 = 49 - 36 = 13, which is prime, so 2 is in the sequence. %e A062573 7^3 - 6^3 = 343 - 216 = 127, which is prime, so 3 is in the sequence. %t A062573 Select[Range[100], PrimeQ[7^# - 6^#] &] (* _Alonso del Arte_, Sep 04 2013 *) %o A062573 (PARI) is(n)=ispseudoprime(7^n-6^n) \\ _Charles R Greathouse IV_, Feb 20 2017 %Y A062573 Cf. A000043, A057468, A059801, A059802, A062572-A062666. %K A062573 nonn,hard %O A062573 1,1 %A A062573 _Mike Oakes_, May 18 2001, May 19 2001 %E A062573 Two more terms (69371 and 86689) found by Predrag Minovic in 2004 corresponding to probable primes with 58626 and 73261 digits. - _Jean-Louis Charton_, Oct 06 2010 %E A062573 New term 355039 found by _Jean-Louis Charton_ in May 2011 corresponding to a probable prime with 300043 digits.